The following U.S. Patents and Applications provide background information and are incorporated herein by reference in entirety.
U.S. Pat. No. 5,537,855 discloses a knock detection method and apparatus that integrates a knock sensor signal over a first period and provides a first integrated knock sensor signal, and integrates the knock sensor signal over a second period and provides a second integrated knock sensor signal. A knock indication is provided dependent on an amplitude of the first integrated knock sensor signal and an amplitude of the second integrated knock sensor signal and independent of the influence of the variations of the knock sensor potential sensor to sensor gain variation.
U.S. Pat. No. 6,845,312 discloses a method for processing knock-related data that reduces the memory locations required for the method and also simplify the processing steps needed to determine a sum, average, and threshold value relating to magnitudes of knock ratios. Inputs from either pressure sensor or accelerometers are filtered and then used to form a ratio between a knock portion of a curve and a reference portion. Sequential magnitudes of the knock ratio are received and analyzed in a manner that reduces required memory locations and improves processing speed.
U.S. Pat. No. 6,932,056 discloses a control method for controlling an internal combustion engine that selects a knock threshold magnitude and compares it to individual knock event magnitudes. The difference between these two values is calculated and limited to be within a predetermined range of values. This limitation selects either an event based control method, a proportional control method, or a control method with characteristics of both techniques. A gain is selected as a function of the algebraic sign of the limited or scaled value and the gain is multiplied by the calculated difference. The result is added to a cumulative value of previously calculated differences multiplied by associated gains. The cumulative value is used as a threshold that activates a plurality of control steps which can include ignition timing changes, fueling changes, or air intake magnitude changes.
U.S. Pat. No. 7,295,916 discloses a method and a device for detecting knocking, in which a measurement signal of a knock sensor is evaluated during combustion in a cylinder of a combustion engine to determine whether the combustion occurred with knocking. The measurement signal is subdivided into a plurality of windows, and in each window an examination is performed to determine whether the combustion occurred with knocking. For a final assessment of whether the combustion occurred with knocking, the events of windows are compared to each other.